The invention concerns a method and an apparatus for producing a tubular packaging casing according to the preamble of claims 1 and 10. In particular, the invention concerns a method for producing a tubular packaging casing, wherein a film web is fed in a feeding direction to forming means for forming a tubular casing having edge areas which extend in the feeding direction and which are arranged adjacent to each other, and the edge areas are bonded together in a bonding station having at least one bonding tool. Furthermore, the invention concerns an apparatus for producing a tubular packaging casing having film web storage means for accommodating a supply of a film web, forming means for forming a tubular casing out of the film web being fed from the film web storage means in a feeding direction to the forming means wherein the tubular casing has edge areas which extend in the feeding direction and which are arranged adjacent to each other, and a bonding station having one bonding tool.
In the process of producing sausage-shaped products, like sausages, tubular packaging casings are used in which the content of the sausage-shaped products, like meat, adhesive, sealing material and the like is filled in. These tubular packaging casings can be provided in a premanufactured form or can be produced just before the filling process is carried out. In the latter case, a film web is used which is fed to forming means for forming a tubular casing. Subsequently, the edge areas of this just formed tubular casing are bonded together and the so produced tubular packaging caring can immediately be used for filling in the content of sausage-shaped product by a filler. Afterwards, the tubular packing casing filled with the material of the product can be closed on both ends by, for example, a clipping machine.
For producing a tubular packaging casing, a method is known from EP patent application 1 435 791, wherein a film web is formed to a tubular casing the edge areas of which are arranged side-by-side to each other for being bonded together by a heat sealing bar. For that purpose a strip of film is used for overlying the edge areas, wherein said strip of film can be an external one or can be cut from the film web before being formed to a tubular casing. The external or cut film strip is placed over the edge areas of the tubular casing, before the heat sealing bar bonds the edge areas of the tubular casing via the strip of film together to produce a tubular packaging casing.
It is further known from EP patent application 0 050 702 to manufacture tubular packaging casings by bonding longitudinal edge areas of a film web formed in a tubular shape by adhesive bonding. The edge areas are arranged side-by-side or overlap each other, and are bonded by a strip of film, carrying an adhesive layer and being pressed with its adhesive side against the edge areas by a roll.
The addressed prior art shows the disadvantage, that the used bonding process has to be chosen according to the material of the film web used for producing a tubular packaging casing. For example, a cellulosic film material can only be processed by an adhesive bonding using a strip of adhesive wherein the machine for executing this process must be equipped with the respective components, in particular a roller for compressing the edge areas and the adhesive strip together. If, on the other hand, a thermoplastic film material is used the edges areas of which are to be bonded together for producing a tubular packing casing, a heat sealing process has to be applied. The machine for carrying out the heat sealing process must also be equipped with specified components allowing the execution of that method, like a heat sealing bar. Thus, separate machines have to be provided if such different materials are used for producing tubular packaging casings. The provision of different machines is, however, of disadvantage, in particular under an economical point of view since, if the one machine is in line with the other machines for filling and closing the sausage-shaped product, the other is out of operation. Moreover, work space for two machines must be provided.
Therefore, it is an object of the present invention to provide a method and an apparatus for producing a tubular packaging casing which allow the use of different film web materials in an efficient way.